This study is designed to evaluate the effect of HHHFNC as compared to NCPAP on lung function as a measure of lung injury in preterm infants born at 28 to 37 weeks gestation requiring continuing respiratory support. In this study, infants will remain on the assigned treatment of either NCPAP or HHHFNC until they require more support as provided by a respirator or until a treatment cross-over from NCPAP to HHHFNC, or the reverse, as decided by their attending physician. The infant's respiratory support will be managed according to his/her attending doctor as per accepted standards of care. A pulmonary function test will be performed twice weekly on each enrolled infant while receiving either NCPAP or HHHFNC support, followed-up by once weekly lung function measurements post respiratory support while infants are breathing only room air until discharge.